The present invention relates in general to a rapid transit system and in particular to a guided transportation system in which the load carrying vehicles are supported on a wedge of pressurized fluid above a transversely curved track surface.
The rapid, efficient transport of people and cargo is fast becoming a high priority concern for governments at all levels. Cities are becoming clogged with automobiles belching forth toxic impurities, the automobiles often carrying but one person each. Fuel supplies are becoming scarce and rationing thereof is in the forseeable furture. It therefore becomes imperative to examine other modes of transport, especially for the "commutor" who travels the same route daily to and from his place of business. The bicycle is one alternative; rapid mass transport is another.
In the latter category great strides have been taken recently in attempts to obtain optimum carrying capacities and speeds for relatively low energy expenditures. Vehicles using air cushions, magnetic attraction or magnetic repulsion for support above a guiding track have been proposed, and in some instances produced. These vehicles may use linear induction motors, jet engines or mechanical interaction with the track for propulsion therealong.
None of the systems proposed to date may properly be considered an optimum system for each has its own particular and peculiar drawbacks. And, considering the rate of advancement in the field, a system which enjoys popularity today may be obsolete by tomorrow.
The air cushion vehicle, for example, has been known for some time and considerable effort has been expended in adapting it to a tracked configuration whereby it may be "trained" with other such vehicles for the transport of passengers and cargo over predetermined routes. These routes may take the form of rails or tracks which are particularly adapted to the vehicle configuration and often take the form of an inverted "T" in cross-section. The vehicle is then guided by the rail, in the case of the illustrated rail with a portion of the vehicle being adjacent each side of the upright of the rail and with a connecting portion of the vehicle being adjacent the uppermost horizontal surface of the rail. Vertical support is usually by way of air cushions attached to the aforementioned vehicle connecting portion acting on the horizontal surface of the rail upright whereby the vehicle is supported on a cushion of air a small distance above the track.
It is readily apparent that there must also be lateral control of the vehicle relative to the track since contact between the track and the vehicle is definitely not desirable, except under braking conditions. This lateral control may be obtained through the action of horizontal jets of pressurized air acting on the vertical, upright surfaces of the guiding rail. This arrangement can lead to some instability especially in curves where the centrifugal forces generated must be compensated. Compensation can be achieved by altering the relative strengths of the horizontal forces on the inside and the outside of the curve, or by banking the track. Either alternative requires considerable engineering skill in view of the low friction conditions achievable with the air cushion effect. The use of wheels for guiding or support of the vehicle would reduce the speeds attainable by the vehicle and would increase noise, power requirements and vibration, each a variable which is desireably kept at a minimum.